This Bible contradiction is from the EvilBible.com.
Exodus 32:27 View context
And he said unto them, Thus saith the LORD God of Israel, Put every man his sword by his side, [and] go in and out from gate to gate throughout the camp, and slay every man his brother, and every man his companion, and every man his neighbour.
Exodus 20:13 View context
Thou shalt not kill.